Implement v4.6.0: sweep Live Activity, share extension, iPad split view, actionable notifications

- Sweep Live Activity: SweepActivityAttributes (Shared/), lock-screen + Dynamic
  Island UI in the widget extension, driven by SweepActivityController wired into
  the batch pipeline (begin/update/end); NSSupportsLiveActivities in Info.plist.
- Share extension (DomainDigShareExtension): accepts a web URL from the share
  sheet, extracts the host, and hands it to the app via the App Group inbox
  (DomainDigShareInbox); the app consumes it on activation and inspects it.
- iPad layout: RootTabView uses NavigationSplitView in the regular size class
  and the tab bar in compact.
- Actionable notifications: per-domain threadIdentifier grouping, a Re-inspect
  action, and tap routing into the domain detail via the intent router.
- Bump version to 4.6.0 (build 38) across app, widget, and share targets.

1 files changed, 25 insertions, 0 deletions

diff --git a/Shared/SweepActivityAttributes.swift b/Shared/SweepActivityAttributes.swift
new file mode 100644
index 0000000..ee03c2d
--- /dev/null
+++ b/Shared/SweepActivityAttributes.swift
@@ -0,0 +1,25 @@
+import ActivityKit
+import Foundation
+
+/// Live Activity contract for an in-flight watchlist sweep or batch lookup.
+///
+/// Lives in `Shared/` because the app starts/updates the activity and the
+/// widget extension renders it.
+struct SweepActivityAttributes: ActivityAttributes {
+    struct ContentState: Codable, Hashable {
+        var completed: Int
+        var total: Int
+        var currentDomain: String?
+        var changed: Int
+        var warnings: Int
+
+        var fractionComplete: Double {
+            guard total > 0 else { return 0 }
+            return Double(completed) / Double(total)
+        }
+    }
+
+    /// User-facing title for the run, e.g. "Watchlist Sweep" or "Batch Lookup".
+    var title: String
+    var startedAt: Date
+}